The white box is a built in power converter so you should be fine with plugging it in as long as you have the adapter that changes plug types. You can check to see if other things are converters if it has something like Input: 100-240V~1.5A 50-60Hz. This shows that an electric current of 100-240 Volts can power the converter without problem, which Spain's electricity falls in. If you cannot find this on a product (though most electronics made in about the last 5-10 years automatically convert) or if you feel you would rather side with caution you can but a converter, but only leave it plugged it when you need the power because converters burn out quickly from overheating if you leave them plugged in too long.

I bought this charger last week, and it does not charger my 11 inch 2010 Macbook Air. The green light comes on but it will not charge my computer, and I've tried everything. I need to know the return policy so that I can get a refund of at least another charger.

Low tech woman seeks simple answers and solutions for bringing my Mac Air laptop on a plane to Germany and being able to travel to nearby countries and have the power cord and voltage be compatible. I saw something online for an airplane power mag cord which can be used. I saw the World Travel Kit for Apple online, but I'm not sure if this is overkill. What's the minimum requirements I will need?

Yes you can. It works, fine for mine. Since I have both Mac books. I am only using the 85w. You can use a higher watt to charge a lower watt item. Just you cannot use a lower watt for a higher item. Go read a few and they all agreed.

The 85W MagSafe Adapter is the adapter that will power (and charge the built-in battery) for 15" (current & past) and 17" (past) MacBook Pro laptops including the retina screen ones, from the wall outlets. It may, also be safely used, in the 13" Macbook Pro's as well as MacBook Air Series.

STANDARD MAINTENANCE:
For proper maintenance of a lithium-based battery, it’s important to keep the electrons in it moving occasionally. Apple does not recommend leaving your portable plugged in all the time. An ideal use would be a commuter who uses her notebook on the train, then plugs it in at the office to charge. This keeps the battery juices flowing. If on the other hand, you use a desktop computer at work, and save a notebook for infrequent travel, Apple recommends charging and discharging its battery at least once per month.

LONG-TERM STORAGE:
If you don’t plan on using your notebook for more than six months, Apple recommends that you store the battery with a 50% charge. If you store a battery when it’s fully discharged, it could fall into a deep discharge state, which renders it incapable of holding any charge. Conversely, if you store it fully charged for an extended period of time, the battery may experience some loss of battery capacity, meaning it will have a shorter life. Be sure to store your notebook and battery at the proper temperature.